DiPietro, who has been plagued with knee and hip injuries, suffered a concussion two weeks ago after being hit in the mask by a teammate’s shot in practice. He had been skating with the team, and had dressed as the backup goalie to Nabokov for Tuesday night’s contest, also against the Penguins.

Nabokov started the Islanders’ previous three games, losing them all, though he played well in each, including a 30-save effort last night, and the decision to pull him in favor of DiPietro appeared to be a questionable call.

After the game, Islanders coach Jack Capuano explained why he made the seemingly bizarre move.

“[Nabokov] was fatigued, and he wasn’t feeling well, so I had to put [DiPietro] in,” Capuano told reporters.

DiPietro, not known for his durability, has played a combined 39 games over the last three seasons. He replaced Nabokov, who had started at least 62 games in each of his previous three full seasons in the NHL.

“After the first period, I was getting fatigued. [Capuano] knew about it, and he pulled the trigger,” Nabokov said. “Sometimes you have to be smart and make those decisions. It’s a long season and I think that’s why he made that move.”

In the shootout, the Penguins’ first shooter, Kris Letang, was stopped by DiPietro. Malkin, the second shooter, scored a back-hander after multiple dekes. James Neal, who shot third, missed the net. All three Islanders shooters — Frans Nielsen, P.A. Parenteau and John Tavares — failed to score.

“If one guy couldn’t go, I have all the faith in Ricky, he was great and actually almost had Malkin there. Obviously if you don’t score in the shootout, you aren’t going to win,” Capuano said.

Despite logging zero minutes of ice time, DiPietro was credited with the loss. It was his first action in a regular-season game since April 9 in which he allowed six goals in a 7-4 loss to the Flyers.

DiPietro was 2-1 in shootouts last season, including a win against the Penguins.

The Islanders, who had a 2-0 lead on goals by Nielsen and Matt Martin, have lost four in a row.